Some types of engine control systems may deactivate a portion of an engine's cylinders under specific low load operating conditions. For example, an eight cylinder engine may be operated using four cylinders in some types of low load operating conditions to improve fuel economy. Operation using all of the engine cylinders is referred to as an activated mode, and a deactivated mode refers to operation using less than all of the engine cylinders.
A vehicle selected mode refers to a selectable driving mode of a vehicle. When selected, the vehicle selected mode will modify operation of various systems of the vehicle such as, but not limited to, a vehicle steering system, a vehicle suspension, and a vehicle audio system. Some examples of vehicle selected modes include, but are not limited to, Race, Luxury, Normal, Stealth, City, Sport, and Economy. For example, in Sport mode (or any other mode that enhances powerful driving) various operating parameters of the vehicle are modified to enhance acceleration and as well as the overall driving experience (e.g., the vehicle audio system may provide an aggressive or powerful powertrain sound to the vehicle occupants). The enhanced level of sound provided by the vehicle audio system based on the selected driving mode may be referred to as a sound quality mode.
Although deactivating a portion of the engine's cylinders may improve fuel economy, the sound quality in all of the vehicle selected modes will be affected. For example, the powerful powertrain sound provided by the vehicle audio system in Sport mode may be discontinuous or sharply contrast when compared to the engine sound created by the engine in deactivated mode, which is noticeable to the occupants of the vehicle. Moreover, as the engine transitions from the activated mode to the deactivated mode, this may create a transitioning sound that is noticeable to the occupants of the vehicle. Accordingly, it is desirable to provide a sound enhancement that masks or blends the transitioning sounds from the engine.